1. Field of the Invention
The present invention relates in general to a linear guiding apparatus. More particularly, the invention relates to a linear guiding apparatus which may be utilized in scanners of different sizes and be suited to shafts of different diameters.
2. Description of the Related Art
As image input, process and finishing have evoked public interest, the optical scanner is now the basic equipment for many computer users. The optical scanner is used to scan the text or graphic information of a document, a magazine, a book or a picture. The scanned information is converted to a digital file and then input to the computer for further process. Of the various kinds of scanners, the flatbed scanner is very common. The scan module of the flatbed scanner is installed under a transparent platform to scan the document disposed on the transparent platform by iterative movement. The document is scanned to a digital image file for displaying, recognition, editing, saving or outputting.
The scan module includes a light source, lens, mirrors, CCD sensor and a chassis housing containing thereof. Because the CCD sensor is designed of a line type in one direction, the scan module interactively moves through the document in another direction during the scanning process. Therefore, the driving mechanism of a flatbed scanner is utilized, to move the scan module through a linear guiding apparatus. Then, the image is scanned to the CCD sensor line by line.
FIG. 1A illustrates the front view of the linear guiding apparatus of a flatbed scanner. FIG. 1B illustrates the sectional view corresponding to the cross section line 1B—1B of FIG. 1A. Referring to FIG. 1A and FIG. 1B, the conventional linear guiding apparatus includes a sleeve 104 and a shaft 102 (the figures only shows a portion of the linear guiding apparatus). The sleeve 104 is located in the main body 106 of the linear guiding apparatus 100. The main body 106 can be formed integrally with the chassis housing 108 in a single body. The chassis housing 108 contains optical components and is located in the housing of the flatbed scanner. The sleeve 104 receives the shaft 102. Therefore, when the driving mechanism drives the chassis housing 108, the linear guiding apparatus 100 makes the chassis housing 108 move along the axis of the shaft 102.
The shaft 102 and the sleeve 104 of the linear guiding apparatus 100 must join tightly to ensure the moving direction of the chassis housing 108 straightly. Thus, the inner diameter of the sleeve 104 is designed to match the outer diameter of the shaft 102. However, the outer diameter of the shaft 102 for different style of the scanner is varied, the storage of various sleeves is necessary. Thus, the cost of the linear guiding apparatus is increased.